Power threshold

In the empirical model developed by Y. Shimomura [1], it is assumed that plasma makes a transition from L-mode to H-mode when the power crossing the separatrix () rises above a power threshold ():

The power threshold for the transition to H-mode is calculated using the following formula,

where A_H is the hydrogenic mass in AMU, is the vacuum toroidal magnetic field at major radius R along the flux surface in Tesla, R is the major radius in meters, is the line average density in units of 10²⁰ m^-3 and a is the minor radius in meters. The RMS deviation of this model is 27%.